Braided complex composite parts and methods of forming same

Abstract

A multi-vane structure for incorporation in an aircraft gas turbine engine has vanes of complex geometry made of braided fibers which are continuous about the cavities defined by the vanes. These complex geometry parts are prepared by providing a plurality of removable mandrels, stacking the mandrels along a horizontal axis in a cavity end to cavity end configuration, braiding about the mandrels, cutting the mandrels adjacent the cavity end faces, side stacking the mandrels so the faces are placed in a parallel orientation and molding. Utilizing braided fibers instead of hand lay-up woven fibers eliminates seams and produces cavities having continuous fibers about the periphery thereof which substantially increases the strength and dimensional reproducibly of the part.

We claim: 
     
       1. A braided composite part of complex geometry comprising peripheral walls having curved shaped surfaces which define a cavity, at least one outside surface of said part being a concave shaped surface, the walls made of continuous braided fibers, the braided fibers conforming to the curved shaped surfaces including the concave shaped surface, the walls formed by braiding about a removal mandrel which has a shape to match the shape of the cavity, the mandrel having been removed and the fibers impregnated with a cured resin. 
     
     
       2. The part of claim 1 wherein the walls define a plurality of cavities. 
     
     
       3. The part of claim 2 wherein the walls are produced from continuously braided fibers disposed about a plurality of removable mandrels. 
     
     
       4. The braided composite part of claim 3 wherein each removable mandrel having continuously braided fibers disposed about it, is placed in a side by side relationship prior to resin impregnation and molding. 
     
     
       5. The braided composite part of claim 1 wherein the fibers are from the group consisting of fiberglass, graphite, aramid, polybenzimidazole, ceramic or mixtures thereof. 
     
     
       6. The braided composite part of claim 1 wherein the fiber size is from single or multiple 1K tow to 12K tow. 
     
     
       7. The braided composite part of claim 1 wherein the continuously braided fibers are placed about the removable mandrels with a braid angle of 45°-85°. 
     
     
       8. The braided composite part of claim 1 wherein the cured resin is a thermoset resin from the group consisting of epoxy, phenolic, polyurethane, polyester, vinyl ester, bismaleimide, or polyimide. 
     
     
       9. The braided composite part of claim 1 wherein the cured resin is a thermoplastic resin from the group consisting of polyetheretherketone, polyetherimide, polyarysulfone, or polyamideimide.